Slit lamps are commonly used by opthamologists to examine the human eye. Such lamps typically operate to project a relatively narrow beam of light into a patient's pupil so that the physician can spatially inspect the illuminated regions of the vitreous humour, cornea, anterior chamber, iris, lens and retina. Accordingly, the slit lamps of the prior art are generally constructed into a combination apparatus that includes (i) a series of optical elements to form a slit image of an optical source onto the patient's eye, (ii) a microscope to examine the regions illuminated by the slit image, and (iii) a supporting structure to interface with and immobilize the patient's head.
The complexity and weight of these slit lamps make them generally inappropriate for the bedside examination of adults, and for the examination of infants and other children who tend to resist a structured and still position. In addition, such lamps are quite expensive and can be unaffordable to small clinics.
Hand-held slit lamps are also provided in the prior art. One such slit lamp is described in a 1965 article by Emanuel Krimsky, M. D., entitled "A New Hand Slit Lamp to fit a Penlight Battery Handle." The prior art slit lamp described in this article utilizes a pair of plano-convex lenses to image a straight-filament lamp onto a patient's eye. A standard pen-light battery handle is coupled to the filament and lenses to form an integral and self-powered portable slit lamp unit.
The hand-held slit lamps of the prior art, such as the portable unit described by Dr. Krimsky, have several problems. For example, they are inflexible and thus offer little if any control over the instrument's performance; and they suffer from mechanical short-comings which limit their durability and safety in a clinical environment.
Further, the commercially-available portable slit-lamps are relatively complex, which raises manufacturing and consumer costs. As such, certain rural clinics, and particularly the clinics of under-developed nations, are unable to afford the devices and to benefit by their use.
It is, accordingly, an object of the invention to provide an improved hand-held slit lamp which reduces or eliminates the afore-mentioned problems.
Another object of the invention is to provide a hand-held slit-lamp which is durable and easily controlled by a user of the lamp.
Still another object of the invention is to provide methods for illuminating and controlling a slit image into a patient's eye.
These and other objects will become apparent in the description which follows.